Strain-induced defects as nonradiative recombination centers in green-emitting GaInN/GaN quantum well structures

The origin of the green gap for GaInN/GaN quantum wells is investigated via temperature-dependent time-resolved photoluminescence spectroscopy. A strong correlation between nonradiative lifetimes and total strain energy is observed, although the wells are almost fully strained. We discuss this observation in terms of nonradiative recombination at defects which contribute to a beginning partial relaxation. The formation energy of a defect is likely reduced by the amount of its released strain energy. We therefore expect an exponential dependence of the defect density on this released strain energy. Our measured nonradiative lifetimes are consistent with a cumulative strain driven generation of defects.